Automatic expansion valve



Sept. 30 1924.

v H H MARSHALL.

AUTOMATIC EXPANSION VALVE I Filed Feb. 21

Patented Sept. 30, 1924.

one s'rrss PATENT oFFicE.

HENRY H. MARSHALL, OF WEST HARTFORD, CONNECTICUT, ASSIGNOR TO THE AUTO- MATIC REFBIGERATING COMPANY, OF HARTFORD, CONNECTICUT, A CORPORA- 'EION OF NEW JERSEY.

AUTOMATIC EXPANSION VALVE.

Application flied February 21, 1923. Serial No. 620,450.

To all whom it may concern:

Be it known that l, HENRY H. MARSHALL, a citizen of the United States, residing at West Hartford, county of Hartford, and State of Gonnecticut, have invented certain new and useful Improvements in Automatic Expansion Valves, of which the following is a specification.

My invention relates to automatically controlledexpansion valves for restricting the passage of a fluid from a higher to a lower pressure, as for example in the well known expansion valves of refrigerating machines.

As such; valves are subjected to more or less erosion by the rapid passage of the fluid, there comes a time, with the construction heretofore used, where one "alve serves the double purpose of stop valve and expansion valve, when they are no longer able to completely shut ed the fluid, when the operating condition requires closure, in order to prevent the flooding ot the refrigeration coils.

The object of my invention is to prevent the further leakage that may occur due to the wear of the expansion valve, by working the expansion valve, only as an expansion valve, and bringing into action a supplemental valve, which is of much larger area than the expansion valve and hence will not be subject to wear and which will at a predetermined tall of the high pressure or rise of the low pressure act as a positive shut-ofi' independently of the expansion valve. With such a protection against flooding, any possible wear due to erosion of the expansion valve can be compensated for by the lessened play of the diaphragm controlling such valve and the wear and tear of such valve becomes unimportant.

Further-features of my invention relate to adjusting means for varying the pressure operating on the valves and for assembling and adjusting the valve seats and the various combinations of parts as will be more fully explained hereinafter.

The accompanying drawing shows an embodiment of my invention by a sectional view.

In the drawings is shown at l, a pipe connection to the high pressure supply from a usual condensing pum and at 2 .is shown a similar connection lea ing to the expansion coils of a refrigerating apparatus.- The high pressure pipe communicates with a chamber 3 and in this chamber opening a valve 4 opcrates .to close an opening into an intermediate chamber 5. 'From the intermediate chamber communication is made with low pressure chamber 6 thru expansion valve 7. The valve 4 is a. stop valve that is held against its seat by the action of a spring 8 and is pushed from its seat by a diaphragm 9 when the pressure in chamber 3 is suiticient to overcome the force of the spring 8. A diaphragm 10 operates to close the expansion valve 7 against the action of a spring ll when the pressure in the low pressure chamber 6 exceedsa certain amount. To adjust and regulate the pressures under which the respective diaphragms and springs shall open and close their valves. i provide nuts 12 which form the back abutments of the springs and are capable of being moved in- Wardlv and outwardly by adjusting screws 13. These screw stems may have their ends squared oil as at 14 so that a wrench may be used for adjusting and caps 15 are provided to close in the ends While a. gasket 16 insures that the fluid may not escape, nor moisture enter. The nuts 12 are guided by ribs or slots 17 in the casing so that they will not turn with the screw. By making the 0 ening controlled by the stop valve 4 larger t an the opening controlled by the expansion valve 7 the pressure in the intermediate chamber 5, when the stop valve is open, will be practieall the same as the high pressure in the chem er 3 so that all the expanding and consequently all the wiring-drawing and erosion wlll take place at the valve 7 and even if this erosion should be so much as to prevent the expansion valve from shutting off the high ressure, it will still not as an expansion va ve by a slight adjustment of the screw 13 and as the stop valve t will immediately close tight upon a reduction of the pressure in the chamber 3 as occurs for instance, when the compressor is stopped there will ensue no flooding of the low pressure coils connected with pipe 2, although withilli out such stop valve this would be certain to occur. The intermediate chamber has a removable cover 18 secured by bolts 19 and sealed with a lead. gasket 20. When this cover is removed access is had to the adjustable valve seats 21 of the expansion valve and 22 of the stop valve with their check nut deleterious erosion.

1. The combination with an expansion valve of a stop valve on the high pressure side having an opening larger than the expansion valve, means contro led by pressure for opening the stop valve during the normal operation of the expansion valve and for closing the sto valve simultaneously with the closing of t e expansion valve.

2. In apparatus of the character described, the combination of an expansion valve and a stop valve with an intermediate chamber, adjustable seats for said valves and a removable cover for said intermediate chamber permitting access to said seats.

3. The combination of an expansion valve controlled by the pressure in the low pres-.

sure side and an automatic stop valve controlled by the pressure on the high pressure side with an intermediate chamber between them, the expansion valve having less area than the stop valve so as to avoid wire-drawing of the latter.

4. An expansion valve comprising a high pressure chamber, a low ressure chamber and an intermediate cham er, a stop valve between the high pressure and intermediate chambers, means controlled by the high pressure for opening and closing the same, and an expansion valve between the intermediate and low pressure chambers controlled by the low pressure, the ratio between the area of the two valve being such that the expansion will all take place at the expansion valve.

5. The combination of a valve casing having a high pressure chamber, a low pressure chamber, and an intermediate chamber of relatively small capacity, a stop valve between the high and the intermediate chambers and an expansion valve between the intermediate and the low pressure chambers the stop valve exceeding the dimensions 01 the expansion valve by an amount sufiieient to prevent ex ansion at the stop valve, and means control ed by pressure for opening the stop valve during the normal operation of the expansion valve and for closing the stop valve simultaneously with the closing of the expansion valve.

6. In an expansion valve of the character described, the combination of an expansion valve and a stop valve with an intermediate chamber, adjustable seats for said valves and a removable cover on said chamber for furnishing access to said adjustable seats.

HENRY H. MARSHALL. 

